/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */

package org.apache.commons.exec.launcher;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.apache.commons.exec.CommandLine;
import org.apache.commons.exec.util.StringUtils;

/**
 * A command launcher for VMS that writes the command to a temporary DCL script
 * before launching commands. This is due to limitations of both the DCL
 * interpreter and the Java VM implementation.
 *
 */
public class VmsCommandLauncher extends Java13CommandLauncher {

	/**
	 * Launches the given command in a new process.
	 */
	@Override
	public Process exec(final CommandLine cmd, final Map<String, String> env) throws IOException {
		final CommandLine vmsCmd = new CommandLine(createCommandFile(cmd, env).getPath());

		return super.exec(vmsCmd, env);
	}

	/**
	 * Launches the given command in a new process, in the given working directory.
	 * Note that under Java 1.3.1, 1.4.0 and 1.4.1 on VMS this method only works if
	 * {@code workingDir} is null or the logical JAVA$FORK_SUPPORT_CHDIR needs to be
	 * set to TRUE.
	 */
	@Override
	public Process exec(final CommandLine cmd, final Map<String, String> env, final File workingDir) throws IOException {
		final CommandLine vmsCmd = new CommandLine(createCommandFile(cmd, env).getPath());

		return super.exec(vmsCmd, env, workingDir);
	}

	/** @see org.apache.commons.exec.launcher.CommandLauncher#isFailure(int) */
	@Override
	public boolean isFailure(final int exitValue) {
		// even exit value signals failure
		return exitValue % 2 == 0;
	}

	/*
	 * Writes the command into a temporary DCL script and returns the corresponding
	 * File object. The script will be deleted on exit.
	 */
	private File createCommandFile(final CommandLine cmd, final Map<String, String> env) throws IOException {
		final File script = File.createTempFile("EXEC", ".TMP");
		script.deleteOnExit();
		try (PrintWriter out = new PrintWriter(new FileWriter(script.getAbsolutePath(), true))) {
			// add the environment as global symbols for the DCL script
			if (env != null) {
				final Set<Entry<String, String>> entries = env.entrySet();

				for (final Entry<String, String> entry : entries) {
					out.print("$ ");
					out.print(entry.getKey());
					out.print(" == "); // define as global symbol
					out.println('\"');
					String value = entry.getValue();
					// Any embedded " values need to be doubled
					if (value.indexOf('\"') > 0) {
						final StringBuilder sb = new StringBuilder();
						for (int i = 0; i < value.length(); i++) {
							final char c = value.charAt(i);
							if (c == '\"') {
								sb.append('\"');
							}
							sb.append(c);
						}
						value = sb.toString();
					}
					out.print(value);
					out.println('\"');
				}
			}

			final String command = cmd.getExecutable();
			if (cmd.isFile()) {// We assume it is it a script file
				out.print("$ @");
				// This is a bit crude, but seems to work
				final String[] parts = StringUtils.split(command, "/");
				out.print(parts[0]); // device
				out.print(":[");
				out.print(parts[1]); // top level directory
				final int lastPart = parts.length - 1;
				for (int i = 2; i < lastPart; i++) {
					out.print(".");
					out.print(parts[i]);
				}
				out.print("]");
				out.print(parts[lastPart]);
			} else {
				out.print("$ ");
				out.print(command);
			}
			final String[] args = cmd.getArguments();
			for (final String arg : args) {
				out.println(" -");
				out.print(arg);
			}
			out.println();
		}
		return script;
	}
}
